Any real hp/ tq gains from catback systems?

[dieselfan1]

I'm putting a Borla Touring catback setup on my 22 HC 6.2.

They all say hp gains but don't back it up with dyno numbers.

I've heard as much as 18 hp gain.

I'm sure that's at 5600 rpm.

What's the real gain if anyone knows?

[richard wysong]

I would be surprised if there was any significant gain without changing the front of the system and the cats because that's where the system is more restricted other than the flapper and possibly the muffler. an internal combustion engine is nothing more than an air pump so the more efficiantly it can get the air in and out the more hp it  can  produce. any modification made to the front of the system would have to be EPA certified and would probably void the warrantee

[newdude]

Eh.  Sound mostly, if there are any power gains, its almost always at an RPM you don't see on the daily at lik 5500-6000rpm.  

 

Butt dyno, I had zero difference in power or MPGs after adding my Corsa and the GM CAI to my 2019 old body.  I have before and after dyno #s from when I had it tuned, those bits made near zero impact.  

 

Long tube headers with high flow cats and a tune?  Yes, you'd see gains.  

[Bikerjon]

The only way to get accurate numbers is to dynamometer test your truck for H.P. and TQ. before and after the exhaust install. I agree with Richard you will probably see a very modest increase in H.P. and TQ. The dyno doesn't lie. If you do the testing I'm sure a lot of us would like to see the results.

[CamGTP]

Exhaust and intake companies will say they're gains because in one small section from say 2800-3400rpm it gained 15hp or some crap so they slap that on the box. The .8 seconds it spends in that rpm section is totally noticeable.

[AJMBLAZER]

Again, gone are the days when factory systems were undersized, crimp bent, poorly routed, and the cats and mufflers were horrible flow restrictors.  Now at best you're getting a less restrictive muffler and eliminating whatever the flapper causes.

 

Especially with a 6.2L where the exhaust is already 3.5"...why replace all that perfectly good pipe?

[TNTSierra]

Because the factory pipe has shitty flappers in it and welding in a new muffler especially in winter areas will eventually rot out, if not welded properly, and with all the $hit they throw on the roads here in Iowa.  Seen it first hand at fathers shop before he retired.
 Plus you have the “hit or miss” on drone and other obnoxious sounds. Man haven’t we been through this before.

 

And we are talking about $1200! Compared to a $60-$70k truck. If you can’t afford that. Don’t be buying the d@mn truck! 
 

Corsa claims 17HP

 

GM performance exhaust which is Borla combo claims 15HP-9 TQ 

 

there is a slight acceleration increase if driven hard. Mine truck has seen .3 secs increase.  Not sports car by any means but the sound of Corsa wide open is intoxicating. No increase for me on MPGs.  
 

 

[AJMBLAZER]

Your money to spend. 
 

You can also repaint it any color you want and put Lambo doors on it. It’s yours. Also doesn’t make it any better. 
 

If you’re letting a crappy exhaust shop that can’t weld do your work then that’s your fault. 

Edited May 18, 2022 by AJMBLAZER

[dna9656]

The physics say you can't get more flow than the smallest opening the gases flow through. If you got a 3" Y pipe that's the max you're going to get, even if you put a 6" pipe on it from the 3" point it's flow no better than the 3" allows. That's the physics. Just like water, you can't get 4" flow from a 2" source pipe by connecting the 4" to the 2". Stay with the same size as the smallest opening your system has. The cat will flow X, you can't get better than that in a CAT back system. Maybe if you ran headers you could increase the flow, but it would still be no better than the smallest hole the exhaust passes through.

You'd need a cat that has that same size diameter inlet and outlet as your upstream pipes

Edited May 18, 2022 by dna9656

[CamGTP]

A $8 can of exhaust paint can stop rust too lol.

Edited May 18, 2022 by CamGTP

[richard wysong]

an old trick with race car headers was to remove all the paint, install them and wipe all the paw prints off them then paint them with ATF start it up and get them good and hot, glowing if possible and when the ATF burns off it leaves the headers gun metal gray and they won't rust. they also make a stainless appearing exhaust paint that works on the same principle

[TNTSierra]

3 hours ago, AJMBLAZER said:

Your money to spend. 
 

You can also repaint it any color you want and put Lambo doors on it. It’s yours. Also doesn’t make it any better. 
 

If you’re letting a crappy exhaust shop that can’t weld do your work then that’s your fault. 

It is my money. And I spend it right the first time! 
 

and even the best weld can rust and rot my friend! Mother Nature and the elements beat the ****** out of things!  She always prevails. 

[KARNUT]

Well I learned a few things from exhaust threads. I had a really good and rare bender. There’re rust problems up north. Strangely I grew up in New Jersey exhaust seemed to last fine then. There’s really not much to gain with cat back exhaust these days. I knew that. That’s why the last few trucks I just changed the muffler. So even if you periodically had to replace a benders muffler from rust. It would take a few before you hit the cost of a cat back. That really doesn’t gain a lot of horsepower anyway. I’m not cheap, just practical. 

[richard wysong]

The factory stainless pipes will last the life of the truck, the muffler will probably rot from the inside out  at some point. They make stainless replacement mufflers that can be clamped on. replacing cat back on a new truck seems foolish to me but it's your $. I agree the welds are the weak point in salt states

[Bikerjon]

Again I agree with Richard. Stainless pipes will last as long or longer than the truck. I only replaced the muffler, cut out the flapper and had it welded into place. $156.00 installed. No droning. The exhaust note is a very personal thing. Some love it, some hate it. I'm sure Borla, Corsa etc. are nice systems just very expensive.